To coincide with World Hepatitis Day, an Article is being published Online First by The Lancet detailing the first global estimates of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection prevalence in injecting drug users (IDUs). Around 10 million IDUs are thought to have been exposed to HCV (range 6 to 15 million), or approximately 67% of the global IDU population, while 1.3 million have HBV infection (range 0.3 to 2.7 million), conclude the authors, that include Professor Louisa Degenhardt, Centre For Population Health, Burnet Institute, Melbourne, Australia and Paul Nelson from the National Drug and Alcohol Research Centre at the University of New South Wales (UNSW). The study was funded by the US National Institutes of Health, the World Health Organization's HIV Department, and the National Drug and Alcohol Research Centre, UNSW.
The authors say: "The public-health response to blood-borne virus transmission in IDUs has mainly centred on HIV. Maintenance and strengthening of the response to HIV in IDUs remains crucial, but the significance of viral hepatitis needs to receive greater attention than it does at present."
The costs of HIV drugs once made their use in resource-poor countries unlikely; but global efforts have ensured that access to these drugs has substantially improved for people living with HIV in developing countries. The authors say: "There are growing efforts to bring viral hepatitis treatments into the same (lower cost) access framework as HIV antiretrovirals." These efforts are reflected in the Viral Hepatitis resolution passed by the 63rd World Health Assembly in 2010, which requested the WHO Director General "to collaborate with other organizations in the United Nations system, partners, international organizations and other relevant stakeholders in enhancing access to affordable treatments in developing countries."
Access to treatments for viral hepatitis must also be enhanced in high-income countries, with recent estimates suggesting that only a fraction of those who could benefit are currently receiving antiviral therapy.
About 80% of individuals exposed to HCV develop chronic infection, and 3% of people with chronic HCV infection will develop liver cirrhosis within 20 years, with associated risks of liver failure and liver cancer. HBV is transmitted through parenteral, sexual, and mother-to-child routes. About 5% of adults exposed to HBV develop chronic HBV infection, compared with 90% of infants; this is why most of the 350 million chronically infected people worldwide were infected in childhood. It is also why universal infant vaccination against hepatitis B is so crucial to long term control of this virus, which is the second most important known human carcinogen, after tobacco. Cirrhosis and death from liver cancer are important consequences of HBV infection, occurring in approximately one quarter of those chronically infected.
In this study, infection was determined via presence of hepatitis C antibody (anti-HCV) and hepatitis B core antibody (anti-HBC) or surface antigen (HBsAg). For hepatitis C infection the authors located eligible reports with data for prevalence of anti-HCV in IDUs for 77 countries. Prevalence estimates suggested that 60% of IDUs had anti-HCV in 25 countries, including Spain (80%), Norway (76%), Germany (75%), France (74%), USA (73%), China (67%), Canada (64%); and more than 80% of IDUs did so in a further 12 countries, including Italy (81%), Portugal (83%), Pakistan (84%), Netherlands (86%), Thailand (90%) and Mexico (97%). The United Kingdom (50%), New Zealand (52%) and Australia (55%) all had lower prevalence. China (1•6 million), USA (1•5 million), and Russia (1•3 million) are thought to contain the largest IDU populations infected with HCV.
HBV infection among IDUs was estimated from eligible reports of HBsAg for 59 countries, with prevalence estimates of 5% in 21 countries and more than 10% in ten countries, including the USA at 12%. The UK had the highest rate in Western Europe at 9%. Worldwide, the highest rates were seen in Vietnam (20%), Estonia (19%), Saudi Arabia (18%), and Taiwan (17%). The authors estimate that globally 6•4 million IDUs have ever been infected with HBV (anti-HBc positive), with 1•2 million having active HBV infection (HBsAg positive).
The authors say: "Efforts to prevent, treat, and reduce harms related to liver disease in IDUs are essential—especially in situations in which HIV has successfully been prevented or managed—because the large numbers of IDUs infected with HCV and significant morbidity resulting from this infection mean that the health and economic costs of HCV transmitted by injected drug use might be as high as (or higher than) those of HIV. Nonetheless, HCV treatment is underused…Part of the reason for this neglect is the high cost, which will remain a substantial barrier to increasing of treatment coverage in low-resource settings until costs are reduced."
The authors stress that not only have prevention, treatment and care been neglected in this field, but also, attention to high quality surveillance of viral hepatitis. They conclude*: "We made the best efforts to identify the most representative studies of IDUs across countries, but there was considerable variation in the quality and recentness of the studies that these estimates are based upon. This reflects a similar lack of emphasis upon surveillance of viral hepatitis among people who inject drugs, as there has been upon prevention and treatment of these viruses. Until there are a more coordinated and sustained efforts to understand and respond to hepatitis, considerable uncertainty will remain in our estimates of the scale of the problem, and the best way to respond."
In a linked Comment, Dr Joseph J Amon, Health and Human Rights Division, Human Rights Watch, New York City, USA, says: "Large between-country variations emphasise how high rates of hepatitis B, hepatitis C, or HIV infection in drug users are not inevitable. Moreover, the estimates provide a powerful means for health and human rights advocates to question government officials in countries with high prevalences, and to caution governments in countries with low prevalences about the potential costs (human and economic) of failing to put in place, or sustain, effective, rights-based policies. "
He concludes: "This study provides us with a first step and powerful data to draw attention to the problem of viral hepatitis in people who use drugs. The next step is to challenge governments to act, and hold them accountable for implementation of rights-respecting and evidence-based programmes."
Professor Louisa Degenhardt, Burnet Institute, Centre For Population Health, Melbourne, Australia. Contact via Cath Sommerville in Media Relations T) +61 3 8506 2404 / +61 422 043 498 E) louisa@burnet.edu.au
Dr Joseph J Amon, Health and Human Rights Division, Human Rights Watch, New York City, USA. T) +1 917 519 8930 E) amonj@hrw.org
And for World Hepatitis Day Comment, Dr John W Ward, Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, GA, USA. Contact via CDC Press Office. T) +1-404-639-8895 E) NCHHSTPMediaTeam@cdc.gov
Note to editors: *quote direct from authors not found in text of Article
Journal
The Lancet